1. Field of the Invention
The present invention is directed to an oscillating electron source, and in one embodiment to a charged particle beam that oscillates between plural electrodes. Such an oscillating beam may be used to drive other devices, such as a pulsed light source acting as an input to a Raman laser.
2. Discussion of the Background
It is possible to emit a beam of charged particles according to a number of known techniques. Electron beams are currently being used in semiconductor lithography operations, such as in U.S. Pat. No. 6,936,981. The abstract of that patent also discloses the use of a “beam retarding system generates a retarding electric potential about the electron beams to decrease the kinetic energy of the electron beams substantially near a substrate.”
An alternate charged particle source includes an ion beam. One such ion beam is a focused ion beam (FIB) as disclosed in U.S. Pat. No. 6,900,447 which discloses a method and system for milling. That patent discloses that “The positively biased final lens focuses both the high energy ion beam and the relatively low energy electron beam by functioning as an acceleration lens for the electrons and as a deceleration lens for the ions.” Col. 7, lines 23-27.
Free electron lasers are known. In at least one prior art free electron laser (FEL), very high velocity electrons and magnets are used to make the magnetic field oscillations appear to be very close together during radiation emission. However, the need for high velocity electrons is disadvantageous. U.S. Pat. No. 6,636,534 discloses a FEL and some of the background thereon.
Raman lasers are also known, such as in U.S. Pat. No. 6,901,084. Furthermore, considerable research efforts have been made to find ways to integrate Raman laser capabilities with traditional semiconductor processes using silicon. One such effort was detailed in Demonstration of a silicon Raman laser, by Boyraz and Jalai, as published in Vol. 12, No. 21, Optics Express, October 2004.
When an electron hits a surface, it knocks out other electrons known as secondary electrons. A material property is the secondary electron yield (SEY) which is (for a given energy) the number of secondary electrons released per primary electron absorbed. Materials with SEY<1 tend to charge negatively; those materials with SEY>1 tend to charge positively.